£25 for acryclics, which are French manicure style. If you want them painted over with varnish (I don't see why you would pay extra for this as you can do it yourself at home once they've started to grow out, which hides it a little bit) then it will cost extra.
I had acrylics until my own nails grew, I'm also a nail biter. But now my own nails are lovely and long and I have them painted over with shellac, which costs me £15 a time and lasts for 2-3 weeks.